Electronic flashes provide supplemental light for photography to enhance images captured by a camera or other imaging devices. Traditional electronic flashes utilize a bulb filled with gas, such as argon, krypton, neon and xenon, or vapor, such as mercury vapor. When a high voltage is applied to the bulb, the gas or vapor is ionized, allowing electrons to flow through the gas or vapor. These electrons excite the atoms of the gas or vapor, which emit light. The wavelength characteristics of the emitted light depends on the gas or vapor in the bulb. In the case of mercury vapor, the emitted light is ultraviolet light, which is usually converted to visible light using fluorescent material since ultraviolet light is typically not desired.
Recently, light emitting diode (“LEDs”) have been improved to a point with respect to operating efficiency where LEDs are now replacing conventional light sources, even bulbs in electronic flashes. Existing LEDs can emit light in the ultraviolet (“UV”), visible or infrared (“IR”) wavelength range. These LEDs generally have narrow emission spectrum (approximately +/−10 nm). As an example, a blue InGaN LED may generate light with wavelength of 470 nm+/−10 nm. As another example, a green InGaN LED may generate light with wavelength of 510 nm+/−10 nm. As another example, a red AlInGaP LED may generate light with wavelength of 630 nm+/−10 nm. However, since electronic flashes typically need to produce white light for color rendering purposes, different color LEDs such as red, blue and green LEDs are used together in an electronic flash to produce white light. Alternatively, a fluorescent material is introduced into one or more UV, blue or green LEDs in an electronic flash to produce with light using fluorescence.
For different photographic applications, different wavelength characteristics are desired from the supplemental light provided by the electronic flash. Thus, there is a need for an electronic flash, imaging device and method for producing a flash of light in which the color characteristics of the light can be adjusted.